1. Field of the Invention
The present invention relates to a nursing bottle assembly for use primarily, but not exclusively, in feeding babies and infants and to a reusable liner therefor.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Nursing bottle assemblies conventionally comprise a rigid outer casing with a teat arrangement secured on top to enclose the feed. One problem with rigid bottles is the tendency for the baby to ingest air. This ingested air can cause excessive wind and extreme discomfort for the baby. The conventional solution to this problem is to provide a bottle with a disposable flexible inner liner that is used to contain the feed. The inner liner collapses as the feed is taken which reduces the pressure required and the amount of air gulped as the baby sucks on the teat. The collapsing action reduces air ingestion and more naturally mimics the action of the breast. Some bottles with disposable liners can be used in any orientation as the feed is held in contact with the teat no matter the angle of bottle or baby. This is beneficial as it allows babies to feed from any angle but requires the air in the liner and teat to be fully expelled once the bottle is assembled prior to use. Typically, this is done by manually squeezing the liner after final assembly of bottle. However, squeezing the liner in this way can cause it to collapse unpredictably so that pockets of milk form within the liner resulting in the milk supply to the baby being stopped. A further problem is that air can be drawn back into the bottle through the hole in the teat when the baby is not feeding. One solution to these problems is described in WO 2004/098486 which uses a manual plunger mechanism that expels the air from the liner and prevents it from being drawn back in. However, it is necessary for the position of the plunger to be continually adjusted during feeding, which increases the complexity of the assembly by introducing moving parts and makes the assembly more difficult to use.
The use of an inner, flexible liner in a bottle assembly can also result in other problems during feeding. Existing liners prevent the formula milk from being mixed in the liner so that a separate vessel is required for mixing. It is also difficult to measure the amount of feed in a conventional liner part way through a feed as the liner collapses unpredictably. In addition, thin flexible liners may twist as they collapse, thereby cutting off the supply of feed to the teat. This problem is unpredictable and causes frustration for both baby and parent.
The object of the present invention is to provide a nursing bottle assembly which overcomes or substantially mitigates the aforementioned problems.